Rads heating on HW circuit

[Marty1966]

The boiler is a potterton suprema 80L. I’ve gone through the manual online and don’t see any reference to a bypass valve but maybe those familiar with the boiler will know better

 

[Marty1966]

The boiler is a potterton suprema 80L. I’ve gone through the manual online and don’t see any reference to a bypass valve but maybe those familiar with the boiler will know better

 

[Marty1966]

Madrab. As you will see other than being a cramped space with the red gate valve in question as you predicted, the pump as others have noted on a previous post, is on the return circuit And that the pump is at the wrong angle …

 

[Madrab]

OK, it's a Suprima 80L? That's an oldy but goldy regular (Heat only)boiler. It won't have an internal bypass hence the valve. My goodness they haven't half shoehorned all that in have they. That's a bit of a servicing mare by the looks of it.

Not good for the pump shaft to be vertical, premature bearing wear etc but lots are installed horizontally for space reasons or it's under the floor. All it needs though is the pump twisted 90Deg so the shaft is still horizontal.

Yes, that valve looks like a bypass. Pump on the return, not really that much of an issue, pump positioning is more critical in an open vented system in relation to the feed and vent rather than where on the system it is actually placed.

All that being said, still need to understand where abouts the rads that heat up when the HW is on, are piped into the circuit.

Looking at that though, no reason the rads couldn't be moved and ideally change the gate valve for an ABV in place of the gate valve.

 

[Marty1966]

Thanks Madrab. I’ll put a bit of hi viz tape on the two pipes in question and upload another photo

 

[Marty1966]

Hope this shows it much clearer than I can explain it … hopefully it lets you see the two pipes in question that go soley to the bathroom rad causing the issue in question

 

[jeff the gasman]

It’s either piped that way or cylinder return isn’t last tee before boiler and reverse circulation is taking place.
Easy to determine.

 

[Marty1966]

Jeff, it’s piped to that one rad via those two highlighted pipes as all the others are on the main CH loop beyond the zone valves.
Not much room above the boiler but I’m guessing if I could somehow Tee off the main CH circuit into those pipes feeding that one rad that ‘should’ solve it ?

 

[Madrab]

You would need to take the flow pipe (see which one heats up first from cold), probably the top one, to the rad and then tee it into the flow after the CH 2 port valve. The return could possibly stay where it is, depending on how close the main return from the HW cylinder is (reverse circulation). It will also need balanced to ensure it doesn't upset the flow to the other rads on the CH circuit.

 

[Marty1966]

Thanks Madrab, would you still me inclined to leave that gate valve as is ?

 

[Madrab]

The gate valve was the oldy trusted method to install a bypass to ensure minimum low through the boiler on overrun once the 2 port valves shut and the boiler shuts down. These days, we install Auto Bypass Valves (ABV's) to do the same job, especially since TRV's were being used as well as 2 port valves, shutting down the flow.

As long as the gate valve is set properly to allow the min flow the boiler then it's doing the job but it does mean it's not as controlled as an ABV - an ABV is normally closed and when the 2ports/TRV's close the increasing system resistance pushes the ABV open - A gate valve is always open a tad so not as efficient for the boiler.

 

[Marty1966]

Good to know, I’ll get an auto bypass valve in that case whilst I’m in that spacious area

 

[Marty1966]

One question, the fact that the pump is on the return circuit, I assume the Auto ByPass Valve direction is still from Flow to Return and not the opposite way around ?

 

[jeff the gasman]

One question, the fact that the pump is on the return circuit, I assume the Auto ByPass Valve direction is still from Flow to Return and not the opposite way around ?

Yes.

 

[Marty1966]

Two final questions before I begin tomorrow morning!
When it comes to draining down the system do I need to lock the HW zone valve open manually in order to drain the primary circuit ? The CH circuit Im familiar with.
Secondly if I rotate the pump forwards through ninety degrees that should correct the pump angle? I cant rotate it backwards as it will hit the flue elbow.
Again many thanks